Lubricants containing alkyl phenol lactates



. United States Patent GALKYL This application is a division of my copending application, Serial Number 784,030, filed December 31, 1958, now US. Patent Number 3,084,183.

This invention relates to improved extreme pressure lubricants and the method of preparing same. More particularly, the invention is concerned with improve ments in extreme pressure lubricants containing a sulfurized organic compound or a sulfurized organic compound with other extreme pressure agents.

It is well known in the lubricating oil art that the high pressures to which lubricants are subjected in certain types of gears and bearings may cause the protective lubricant film on the gear and bearing surfaces to rupture with resulting damage to gears, bearings and other components. It is further known that base lubricants such as mineral and synthetic oils can be improved with regard to their protective effect on high pressure rubbing surfaces by the addition of certain substances to improve the film on the contacting surfaces by imparting extreme pressure characteristics. Such additive substances, known to the art as extreme pressure additives, strengthen the lubricant film to prevent film breakage and resulting excessive wear, scutiing and seizure, which normally follow a break in the lubricant film under unfavorable pressure and speed conditions. Lubricants having extreme pressure properties are known as extreme pressure lubricants.

In the past, extreme pressure lubricants containing compounds of sulfur have been well known by those skilled in the art and much research has been conducted to discover new and better compounds of sulfur which may be used to impart extreme pressure characteristics to lubricants. Although many formulations of sulfur compounds have been proposed as extreme pressure improvers, no one widely accepted formulation has been discovered. I have found that certain new compositions which do not impart appreciable extreme pressure characteristics by themselves may be added to known sulfurcontaining extreme pressure lubricants and the properties of the extreme pressure lubricants can be thereby markedly improved. Accordingly, the extreme pressure properties of extreme pressure lubricants, particularly those containing sulfur compounds, can be further greatly enhanced and the overall effectiveness of such lubricants can be improved to a large extent by the addition of a minor amount of an oil-soluble alkyl phenol lactate.

In accordance with the present invention, an alkyl phenol lactate is prepared by reacting approximately equimolar amounts of alkyl phenol and lactic acid, and preferable from 1 to 1.1 moles lactic acid per mole of alkyl phenol, under total reflux conditions in the presence of a hydrocarbon diluent such as, for example, naphtha, benzene, toluene, etc. Water is formed as a by-product of esterification and is conveniently removed by a water trap while refluxing. No added catalyst is necessary for the esterification reaction because the acidity of the reactants apparently has sufficient catalylic effect, although known esterification catalysts such as, for example, phosphoric or sulfuric acid, may be employed. A diluent should be chosen to maintain the reflux temperature in 3,215,938 Patented Nov. 9, 1965 'ice the range from about to about 180 or 20 C. preferable from about to about 150 C. After elimina tion of one mole of water per mole of reaction product and any water originally present as an impurity in the lactic acid, a light yellow liquid product is obtained. The naphtha or other suitable diluent is then removed from the yellow liquid product, such as, for example, by evaporation, blowing with a gas such as air or nitrogen, distillation, etc. The remaining liquid has a honey-like appearance and consists of alkyl phenol lactate.

The lactic acid employed in the above reaction may be a commercial grade lactic acid such as one containing from '85 to 90% lactic acid with 10 to 15% impurities, mainly water. The alkyl phenol used in the reaction should have at least from about 7 to about 18 or more total carbon atoms in the alkyl group or groups to provide an alkyl phenol lactate product which is sufficiently oil-soluble for use in lubricant compositions. 'Preferably, the alkyl group or groups should have a total of from 8 to 12 carbon atoms and of specific preference is nonyl phenol. However, other alkyl phenols such as, for example, dibutyl phenol, diarnyl phenol, dihexyl phenol, n-octyl phenol, 2-ethyl hexyl phenol, nonyl phenols, decyl phenols, dodecyl phenols, etc. may be advantageously employed. Where two or more alkyl chains are present, none preferably contains less than four carbon atoms unless one containing at least 7 carbon atoms.

The ester number of the alkyl phenol lactate product, as calculated by subtracting the acid number from the saponification number, is normally in the range of from to 190, indicating a high conversion of the reactants to the ester. However, by stopping the esterification reaction before its completion or by allowing the product to partially hydrolize due to the presence of water, products with lower ester numbers down to about 80 or lower would be obtained. Such products are also useable to enhance the extreme pressure properties of extreme pressure lubricants although larger amounts should advantageously be used because of the lower ester content.

After the formation of the alkyl phenol lactate, the alkyl phenol lactate is advantageously incorporated into sulfur-containing extreme pressure lubricants to further improve their extreme pressure capabilities. The alkyl phenol lactate may be used in concentrations as low as about .003 mole per atom of sulfur of the sulfur-containing extreme pressure agent, but amounts exceeding about 1.0 mole per atom of sulfur of the sulfur-containing extreme pressure agent should not be used because under high pressures and temperatures greater than 3 wt. percent concentrations based on total extreme pressure lubricant, introduce the danger of resulting in harmful deposits on contacting surfaces; however, for effective extreme pressure enhancement, the alkyl phenol lactate should be used in a concentration of at least 0:1 wt. percent. The preferred amount of alkyl phenol lactate for effective extreme pressure improvement is from about .05 to about 0.7 mole per atom of sulfur present in the sulfur-containing extreme pressure agent. The alkyl phenol lactate may be used to improve the extreme pressure characteristics of the sulfur-containing extreme pressure agent in the presence of other extreme pressure components. Such additional extreme pressure agents are chlorine-containing agents, lead-containing agents, phosphorus-containing agents, oxygen-containing compositions such as fatty acids, esters or ketones, and combinations of the above as known in the art.

The sulfur-containing components with which the alkyl phenol lactate may be used in accordance with my invention are those sulfur-compositions or materials useful in extreme pressure lubricants. Thus, sulfurized hydrocarbons, e.g., sulfurized dipentene, etc., sulfurized carboxylic acids, e.g., sulfurized tall oil, sulfurized sperm oil, sulfurized oleic acid, etc., organic sulfides, sulfurized vegetable oils, polysulfides, e.g., the dialkyl tri, tetra-, penta-, and hexasulfides, and other oil-soluble sulfur containing compounds or materials may be employed herewith. Reference is made to US. 2,136,391 and US. 2,202,394 and the art in general for many other sulfurcontaining extreme pressure additives which are generally useful in accordance with the present invention. The expression sulfur-containing extreme pressure agent or similar expression is to be considered descriptive of the sulfur-containing organic constituents exemplified above which may be employed in compounding extreme pressure lubricants. Generally, such sulfur-containing constituents are useful in accordance with this invention in an amount sufficient to alford an effective sulfur content of from about 0.2 to about 3.0% and preferably from about 0.3 to about 1.0% and within the atom ratios with reference to moles of alkyl phenol lactate as set out above. Additional amounts of sulfur may be introduced from extraneous sources such as that which may be contained in the base oil, but such sulfur is not to be included within the foregoing limits since it is not ordinarily effective in imparting extreme pressure characteristics.

Other extreme pressure agents in addition to the above sulfur-containing agents may also be employed in the presence of the sulfur-containing agents and the alkyl phenol lactate. Such other extreme pressure agents include chlorinated compounds, lead compounds, phosphorus compounds and oxygen containing extreme pressure agents. Accordingly, as chlorinated compounds, products obtained by chlorinating paraffin wax or olefinic hydrocarbons have been found to be particularly useful. Chlorinated individual aliphatic compounds such as hexachlorethane, heptachlorpropane, octachlorbutane, etc., are likewise useful. Reference is made to US. 2,178,513 which sets forth a substantial number of halogenated organic ring compounds and US. 2,276,341 which discloses large numbers of chlorinated hydrocarbons and other chlorinated organic materials useful in extreme pressure oils. Such materials may be employed in accordance with the present invention. The chlorine containing extreme pressure additives, if used, should be present in the compositions of the present invention in an amount up to about 8% by total chlorine content and preferably not greater than about 3%. T o be effective in imparting extreme pressure characteristics, the chlorine content should be at least about 0.3% and preferably greater than about 1%.

The lead-containing extreme pressure agents may be any organo-lead compounds known to the art as an extreme pressure agent but preferably should be a lead salt of a higher molecular weight carboxylic acid and of particular preference is lead naphthenate. The lead compound, if used in the compositions of the present invention, may be employed in amounts corresponding to up to about 3.0% lead or higher and preferably from about 0.5 to about 2.0% lead. The phosphorus-containing'cxtreme pressure agents are also well known in the art. Such phosphorus-containing agents may be either trivalent or pentavalent organic phosphorus compounds such as for example esters of the organic phosphorus acids including the alkyl, aryl, and alkaryl esters of alkyl, aryl, and alkaryl phosphor-us, phosphoric, phosphonic, phosphonous, phosphinous, and phosphinic acids or the corresponding thio-compounds. Other organic phosphorus compounds of known extreme pressure characteristics may be used in extreme pressure imparting amounts known to the art. Further, the oxygen-containing organic extreme pressure agents known to the art such as certain fatty acids, esters, or ketones may also be employed in addition to the sulfur-containing extreme pressure agents in the presence of the alkyl phenol lactate.

The sulfur-containing extreme pressure agents whose properties are improved by the alkyl phenol lactate also include those sulfur-containing compositions which also contain chlorine, oxygen, phosphorus, etc. in chemical combination. Such agents are exemplified by the sulfochlorinated hydrocarbons and the phosphorus sulfide-hy drocarbon reaction products known to the art.

closed in US. 2,644,810, are likewise useable. Accordingly, the extreme pressure agents with which the alkyl phenol lactate is useful include compositions having various extreme pressure improving elements chemically bonded in the same compound and are not limited to mixtures of individual compounds.

The lubricants ordinarily employed with the alkyl phenol lactates in the present invent-ion are the mineral lubricating oils of higher viscosities, e.g., of viscosities in the range of from about 45 to about 180 SSU at 210 F. and preferably from about to about SSU at 210 F., and having a sulfur-containing extreme pressure agent as pointed out above. Such lubricants may, of course, in addition to other extreme pressure agents, also contain effective quantities of various other typical lubricant additives such as viscosity index improvers, antioxidants, detergents, corrosion-inhibitors, etc. It should be understood that the lubricants of the type discussed herein are those useful principally in automotive and industrial machinery, e.g., hypoid gears, bearing lubrication, etc., and those lubricants useful in metal rolling operations, etc.

EXAMPLES OF PREPARATION OF ALKYL PHENOL LACTATE EXAMPLE 1 210 grams of nonyl phenol were diluted with 100 cc. of naphtha in a glass reaction vessel which was equipped with a stirrer and thermometer and fitted with a reflux condenser and a water trap. The water trap was adjusted to allow intermittent draining into a graduated cylinder for collection and measurement of water. 100 grams of a lactic acid, having an assay of 85% lactic acid, were added and the reaction mixture was heated while stirring for 18 hours under reflux conditions, the temperature rising from 107 C. up to 220 C. during the reaction. During the first 12 hours of heating, the temperature rose to 140 C. and 27 cc. of water were removed from the reactants. During the remaining 6 hours heating exceeded 140 C. and an additional 3 cc. of water were removed. After heating, the reactants were placed on a steam bath and the naphtha was stripped from the reactants by distillation. 262 grams of a honey-colored viscous liquid product were obtained. The product had an average molecular weight of from 284 to 285, a viscosity of 72.3 SSU at 210 F., an API gravity of 7.9, a neutralization number of 20, a saponification number of 191.0, and an ester number of 171.0. The calculated percent of ester present was 89.0%.

EXAMPLE 2 660 (3 moles) grams of a commercial nonyl phenol were diluted with 300 cc. of naphtha. 330 grams (3.24 moles based on lactic acid content) of Bakers reagent grade lactic acid, having an assay of 87.4% lactic acid, were added to the diluted nonyl phenol in the glass reaction vessel equipped as stated in Example 1. The reaction mixture was heated while stirring for a total of 22 /2 hours, 4 hours of the total being used to bring the reactants to reflux temperature. The reactants were refluxed at from to 140 C. with an average temperature of to 137 C. A total of 96 cc. (3 moles of water from the esterification reaction and 42 cc. of water present in the lactic acid) of water was removed from the reactants. The reactants were then transferred to a Also of, particular usefulness are the sulfur chloride-phosphorus. sulfide-hydrocarbon reaction products such as those dis-t closed in US. 2,727,030. Further, the thiophosphorus" acids, salts and esters such as disclosed in US. 2,422,630,; and the sulfurized organic acids and esters such as dis beaker placed on a steam bath and blown with N 894 grams of a honey-colored viscous liquid product were obtained. The product has a viscosity of 65.7 SSU at 210 F., a neutralization number of 33.3, a saponification number of 192.0 and an ester number of 158.7. The calculated percent of ester present was 82.7%.

EXAMPLE 3 This example was prepared to illustrate a product of low ester content. 100 grams of the product of Example 2 were mixed with 5 grams of Na CO and decanted, filtered and hydrolyzed with a water Wash. The Water insoluble portion was recovered as a product. The product had an average molecular weight of 246:5, a neutralization number of 3.3, a saponification number of 86.5 and an ester number of 83.2. The calculated percent of ester present was 43.3.

EXAMPLES OF ALKYL PHENOL LACTATE AS E.P. IMPROVER Various samples were compounded to prove the effectiveness of the alkyl phenol lactate as an extreme pressure improver. The samples were subjected to the Timken Test to determine ability to withstand heavy load and the CRC designation L-l9-645 hypoid gear oil test. The ingredients of the samples other than the alkyl phenol lactate are all well known extreme pressure additives. For simplicity, the well known extreme pressure additives have been referred to in all samples by abbreviated nomenclature. Definitions of the abbreviated nomenclature follow:

Clorafin 42: A chlorinated hydrocarbon product of Hercules Powder Company containing from about 40 to about 42% reacted chlorine.

CH-73: A chlorinated hydrocarbon product of Pennsylvania Salt Manufacturing Company containing from about 70 to about 73% reacted chlorine.

Sulfurized Sperm Oil: A sperm oil sulfurized with flowers of sulfur at elevated temperatures containing from about to about 12% sulfur.

The Timken Test referred to above is well known to those skilled in the art. The test basically consists of submitting lubricants to the conditions of a Timken testing machine to obtain comparative load-bearing capacities of lubricants, exceedingly valuable information with respect to the potential commercial value of extreme pressure lubricants. The Timken machine and test are fully described in the Journal of the Institute of Petroleum, 32, pp. 209210 and 220-222 (1946).

The following samples were subjected to the Timken Test with the results as indicated in Table I.

Sample 1: 5% sulfurized sperm oil blended in a mineral lubricating oil to give a viscosity of from 85 to 95 SUS at 210 F.

Sample 2: Sample 1 containing 2% of the product of Example 1.

Sample 3: 5% sulfurized sperm oil and 6% Clorafin 42 blended in a mineral lubricating oil* to give a viscosity of from 85 to 95 SUS at 210 F.

Sample 4: Sample 3 containing 2% of the product of Example 1.

Sample 5: 5% sulfurized sperm oil, 3% CH-73, and

5% lead naphthenate blended in a mineral lubricating oil* to give a viscosity of from 85 to 95 SUS at 210 F.

Sample 6: Sample 5 containing 2% of the product of Example 1.

Sample 7: 6% Clorafin 42, 5% lead naphthenate** and 1.76% sulfurized dipentene blended in a mineral lubricating oil* to give a viscosity of from 85 to 95 SUS at 210 F.

Sample 8: Sample 7 containing 1% of a product made in accordance with the procedure of Example 2.

of the product containing 0.3% of the product containing 0.5% of the product containing 1.0% of the product of Example 2.

Sample 14: Sample of Example 2.

Sample 15: Sample 9 of Example 3.

containing 2.0% of the product containing 2.0% of the product blend of Mid-Qontinent 20 Wt. and Mid-Continent 50 wt. mineral oils containing a polyisobutylene polymer viscosity improver.

Basic lead naphthenate having about lead content.

Table I.Results of Tlmken T est Scar Width, Sample Lbs. Pass Lbs, Fail Mm. at Pass Load As demonstrated by the data of Table I, the alkyl phenol lactate improves the extreme pressure properties of extreme pressure lubricants containing sulfur (Samples 1 and 2), sulfur and chlorine (Samples 3 and 4) and sulfur, chlorine and lead (Samples 5 and 6). The alkyl phenol lactate has also been shown to be effective in use in extreme pressure lubricants containing phosphorus and oxygen-containing extreme pressure improvers. The data of Table I further point out the advantageous use with a Wide variety of sulfur-containing and chlorine-containing ingredients. Further Samples 9 to 14 indicate the results from use of varying amounts of the alkyl phenol lactate. Sample 15 shows the usefulness of an alkyl phenol lactate with a low saponification number (about at a resulting lower etficiency but still a marked improvement.

Further, the data of Table I regarding Samples 9 to 14 not only indicate increased extreme pressure characteristics, but also show lessening in scar width when the alkyl phenol lactate is used in concentrations of 0.5% and greater.

The Timken Test as outlined above was also run on the following Samples la through 4a to demonstrate that although the alkyl phenol lactate has little extreme pressure imparting ability in itself, when used in combination with known extreme pressure agents an appreciable improvement in extreme pressure characteristics results. Sample 5a further points out usefulness with oxygen containing extreme pressure improvers. The Timken Test results on the following samples are indicated in Table II.

Sample 1a: A Mid-Continent 50 wt. mineral oil without additives.

Sample 2a: Sample 1a containing 2% of the product of Example 2.

Sample 3a: Sample 1a containing 5% sulfurized sperm oil, 6% Clorafin 42 and 5% lead naphthenate (30% lead).

T Zzble 11 Lbs. Pass Lbs. Fail Scar, Min. at

Pass Load The CRC designation L-l9645 hypoid gear oil test, commonly known as the L-l9 test, referred to above is well known in the art and is published in the 1946 CRC Handbook of the Coordination Research Council. The test was developed by the Coordinating Lubricants Research Committee at the request of Army Ordnance and is designed to test the suitability of lubricants as automotive hypoid gear oils under high speed use. The test employs actual full scale automotive hypoid gears operating under conditions simulating extremely severe service. The following samples of commercial-type gear oils were subjected to the L-19 test with results as recorded in Table III.

Sample 1b: A Mid-Continent mineral with an isobutylene polymer viscosity improver and having a viscosity of 80 to 90 SUS at 210 F. containing sulfurized sperm oil, 6% Clorafin 42. 5% lead naphthenate (30% lead), and 0.6% dodecyl hexasulfide.

Sample 2b: Sample 1b containing 1.0% nonyl phenol lactate.

Table III.Results of L-19 test L-l9 rating lb 3 to 4 *Based on the following arbitrary scale 6Exce1lent passing 5G00l'1 passing 4P0or passing 3Border1ine 2.Partla1 failing 1Faillng 0Badly failing The alkyl phenol lactates herein described may be used to improve sulfur-containing extreme pressure lubricants for use at automotive gear and industrial gear oils. The compositions are further useful to suppress bearing wear and industrial and automotive machinery wear in cases where lubricants may be employed such as in the suppression of cam-follower wear in internal combustion engines. Thus, alkyl phenol lactate may find many uses in extreme pressure lubricants through the above demonstrated improving effect on sulfur-containing extreme pressure lubricants.

The alkyl phenol lactates may be prepared in concentrates containing more than about 10% and up to about 50% or higher of the alkyl phenol lactate in a suitable diluent such as the above-mentioned high viscosity mineral lubricating oils. The concentrate may also contain other additive components for other purposes as well as sulfur-containing extreme pressure agents and other extreme pressure agents. When the sulfur-containing extreme pressure agents are present in the concentrate, they should be present in such amounts in relation to the alkyl phenol lactate so that upon dilution to form an extreme pressure lubricant, the ratio of moles of alkyl Sample:

phenol lactate to atoms of sulfur will be from about .003 to 1.0 to about 1 to 1 and preferably from about .05 to 1.0 to about 0.7 to 1.0.

The above examples and specific formulations of alkyl phenol lactates have been presented as specific embodiments of the compositions of this invention and are not to be considered as limitations to the scope of the invention except as specifically indicated in the claims ap pended hereto. Having set out my invention, it is to be understood that many adaptations and applications thereof will be evident to those skilled in the art and all such adaptations and applications are to be considered within the scope of my invention as fall Within or are equivalent to the definitions of the following claims.

I claim:

1. An extreme pressure lubricant composition comprising a major amount of a mineral lubricating oil, a minor amount of a sulfur-containing extreme pressure agent selected from the class consisting of sulfurized sperm oil, sulfurized dipentene and dodecyl hexasulfide, and from about .003 to about 1.0 mole of an oil-soluble alkyl phenol lactate per atom of sulfur of said sulfur-containing extreme pressure agent wherein one alkyl group has at least seven total alkyl carbon atoms and not more than 18 alkyl carbon atoms on the alkyl groups.

2. The extreme pressure lubricant composition of claim 1 wherein the alkyl of the oil-soluble alkyl phenol lactate contains from 8 to 12 carbon atoms.

3. An extreme pressure lubricant comprising a mineral lubricating oil having a viscosity in the range of from about 45 to about SSU at 210 F. and a sulfur-containing extreme pressure agent selected from the class consisting of sulfurized sperm oil, sulfurized dipentene and dodecyl hexasulfide, and in addition thereto from about .05 to about 0.7 mole of an alkyl phenol lactate per atom of sulfur of said sulfur-containing extreme pressure agent said alkyl phenol lactate having at least one seven carbon atom alkyl group.

4. An extreme pressure lubricant composition comprising a major amount of a mineral lubricating oil, a minor amount of a sulfur-containing extreme pressure agent selected from the class consisting of sulfurized sperm oil, sulfurized dipentene and dodecyl hexasulfide, and from about .003 to about 1.0 mole of an oil-soluble nonylphenol lactate per atom of sulfur of said sulfur-containing extreme pressure agent.

5. An extreme pressure lubricant composition comprising a major amount of a mineral lubricating oil, 0.2 to 3.0 weight percent sulfurized sperm oil based on weight of sufur, and 0.5 to 1.5 weight percent of a nonylphenol lactate.

6. An extreme pressure lubricant concentrate comprising a mineral lubricating oil and from 10 to 50% of a composition consisting essentially of an oil-soluble alkyl phenol lactate and a sulfur-containing extreme pressure agent selected from the class consisting of sulfurized sperm oil, sulfurized dipentene and dodecyl hexasulfide in a ratio of moles of lactate to atoms of sulfur of from about .003 to 1 to about 1 to l and capable of dilution with a mineral lubricating oil to form an extreme pressure lubricant wherein the alkyl phenol lactate has at least seven total alkyl carbon atoms and not more than 18 alkyl carbon atoms on the alkly groups.

No references cited.

DANIEL E. WYMAN, Primary Examiner.

JULIUS GREENWALD, Examiner. 

1. AN EXTREME PRESSURE LUBRICANT COMPOSITION COMPRISING A MAJOR AMOUNT OF A MINERAL LUBRICATING OIL, A MINOR AMOUNT OF A SULFUR-CONTAINING EXTREME PRESSURE AGENT SELECTED FROM THE CLASS CONSISTING OF SULFURIZED SPERM OIL, SULFURIZED DIPENTENE AND DODECYL HEXASULFIDE, AND FROM ABOUT .003 TO ABOUT 1.0 MOLE OF AN OIL-SOLUBLE ALKYL PHENOL LOACTATE PER ATOM OF SULFUR OF SAID SULFUR-CONTAINING EXTREME PRESSURE AGENT WHEREIN ONE ALKYL GROUP HAS AT LEAST SEVEN TOTAL ALKYL CARBON ATOMS AND NOT MORE THAN 18 ALKYL CARBON ATOMS ON THE ALKYL GORUPS. 